Method and apparatus for interworking dispatch services network

ABSTRACT

The voice signaling gateway ( 10 ) converts signaling and bearer traffic information between iDEN network ( 20 ) and various other networks ( 30 - 60 ). The voice signaling gateway includes a signaling portion ( 14 ) and a bearer traffic portion ( 12 ). The voice signaling gateway interfaces with any networks which support session initiation protocol (SIP). Further, the voice signaling gateway is capable of. interworking with both 3G and 2G type networks.

BACKGROUND OF THE INVENTION

[0001] The present invention pertains to supporting dispatch callservices through iDEN networks and more particularly to providing thesedispatch call services through a plurality of non-iDEN networks.

[0002] Today dispatch call services are provided by specialized networkssuch as iDEN (integrated digital enhanced network). A dispatch call isone in which the originator selects a person or persons to which hewishes to speak and the target user's phone immediately transmits thewords of the originator, without the ringing and answering of typicalphone calls.

[0003] The iDEN system is a “closed system” which offers dispatchservices to those customers who are currently in the iDEN TDMA (timedivision multiple access) network. Other networks such as code-divisionmultiple access (CDMA), global system mobile (GSM), internet protocol(IP) and 802.11 type networks do not support dispatch call services atthe present time. Non-iDEN subscribers wish to make dispatch calls tothe existing customer base of iDEN subscribers and vice-versa.

[0004] The users of dispatch call services are typically organized intotalk groups. Talk groups usually contain users that share a commonmission, such as a work group. Work groups may be put together such thatnot all the users are uniformly iDEN or non-iDEN. Current dispatch callservice systems are unable to facilitate the connection of such diverseusers.

[0005] Dispatch systems have been provided to alleviate this problem;however, such patches involve many limitations including missed calls,poor audio quality, and gaps in speech.

[0006] Accordingly, a need exists to provide for dispatch call servicesbetween iDEN users and non-iDEN systems.

BRIEF DESCRIPTION OF THE DRAWING

[0007]FIG. 1 is a block diagram of a system for facilitating dispatchcalls among iDEN networks and various non-iDEN networks in accordancewith the present invention.

[0008]FIG. 2 is a flow chart of a method for interconnecting iDEN andnon-iDEN systems in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

[0009] Dispatch call services are becoming more widespread. Non-iDENsubscribers need to make dispatch calls to the existing customer base ofmillions of non-iDEN subscribers. Additionally, dispatch call serviceproviders desire to provide new services such as desktop dispatchwithout changes to the basic iDEN network infrastructure.

[0010] In a broad sense the present invention includes the introductionof a new network element called a voice signaling gateway (VSGW). TheVSGW provides signaling and bearer path conversion of all trafficbetween an iDEN network and non-iDEN networks. The VSGW is networkagnostic on the non-iDEN network end. The VSGW may be used with CodeDivision Multiple Access (CDMA), General System Mobile (GSM), 802.11(such as Wireless LANs) and traditional Internet Protocol (IP) fordesktop dispatch call services. The present invention does not requirethe iDEN network elements to be modified, nor does the present inventionrequire that the iDEN users be aware that they are communicating withusers on a non-iDEN network.

[0011] Referring to FIG. 1, a block diagram of voice signaling gateway10 interconnected between iDEN network 20 and a number of non-iDENnetworks 30-60 is shown. The voice signaling gateway (VSGW) 10 providesdispatch call services including private call (i.e. PTT “walkie-talkie”like service) and call alert (i.e. PTT non-bearer audio “beep”indication to called party) which is interworking between legacy iDENsystems and non-iDEN systems such as session initiation protocol (SIP)based 3 G systems. SIP is a protocol that is used for setting up singleor multi-party calls. SIP is defined by IETF RFC3261. The VSGW 10communicates in the SIP protocol with other networks that support SIP.

[0012] The VSGW 10 allocates bearer resources for SIP to DAP dispatchcalls. DAP is a dispatch application server that processes dispatchrequests within the iDEN network 20. VSGW looks like a DAP on the iDENnetwork 20 side and a SIP engine on the non-iDEN side. The iHLR 22 isthe iDEN home location register. The iHLR is a database that includessubscriber records/profiles and rules that dictate how a dispatch callshould be handled. The iHLR is the place where iDEN subscriber 21, forexample, is registered and the network which provides service tosubscriber 21. The iHLR 22 stores the subscriber profile and records andthe identity of the DAP 24 that the subscriber is registered.

[0013] iDAC 26 is the iDEN dispatch audio controller. For the iDENnetwork 20, the iDAC 26 handles the voice payload. DAP 24 providesbearer traffic control to iDAC 26 via connection 25. VSGWb 12 of voicesignaling gateway 10 behaves like iDAC 26. Standard RTP 15 and iDEN RTP16 convert back and forth between the two real time protocols. iDEN RTPis used by the iDEN network 20 and standard RTP is used by the non-iDENnetworks 30-60. RTP is defined in IETF RFC1889. The protocol conversionis performed by VSGWb 12.

[0014] DAP 24 is coupled to DAP 17 of VSGWs. DAP-DAP signaling is aproprietary signaling protocol used between DAP 24 and DAP 17. DAP 24 isthe call engine that processes dispatch requests for iDEN network 20.

[0015] iHLR 22 of network 20 is coupled to DAP 17 of VSGWs 14. MAP is anabbreviation for mobile application part and is a standard basedprotocol which enables real time communication between nodes in a mobilecellular network. A typical use of the MAP signaling protocol is thetransfer of location information from a visiting location register (VLR)which is within the DAP to the iDEN home location register (iHLR) 22.MAP includes a layer in the signaling system seven standards which isused by GSM networks and UMTS (Universal Mobile TelecommunicationsSystem). The standard is defined by ETSI TS129120V3.0.0. SIP 19 of VSGWS14 provides SIP signaling on the SIP signaling lead. SIP signaling is aprotocol that is used for setting up single or multi-party calls.

[0016] The SIP signaling lead couples SIP 19 to CDMA (code divisionmultiple access) network 30, GSM (global system mobile) network 40,802.11 (such as Wireless LAN) network 50 and internet protocol (IP)network 60.

[0017] Further, the VSGW 10 includes PiHLR 27. iHLR stores user profileinformation for 2G dispatch users. PiHLR 27 is a pseudo-iHLR used tostore location information for 3 G dispatch users.

[0018] Referring to FIG. 2, a flow chart of the operation of the voicesignaling gateway 10 is shown. The process is started and block 70 isentered. Block 70 waits for a message from one of the networks 20 or30-60. Upon receipt of a message, block 70 transfers to block 72 whichdetermines the message type. The message type indicates one of threeconditions. The conditions are an initial request, a setup in progressor in-call modification (i.e. bearer packets).

[0019] For an initial request, block 72 transfers control to block 74.Block 74 determines whether the destination of the voice message isknown. If the destination is not known block 74 transfers control toblock 76 via the no path. For a request to non-iDEN networks 30-60, adatabase query 76 is made to a domain name server (not shown). For arequest to the iDEN network 20, database query 76 interrogates the iHLR22.

[0020] Block 76 then transfers control to block 78. If the destinationof the packet was known, block 74 transfers control directly to block 78via the yes path. Block 78 determines whether the resources may beassigned to service this dispatch call. If the resources can be assignedblock 78 transfers control via the yes path to block 98. This indicatesthat the initial message does not specify the desired resource orresource options. For initial messages that do not specify resourceoptions, resources cannot be assigned and block 78 transfers control toblock 80 via the no path.

[0021] Block 80 generates a resource list which is offered to the sourceof the dispatch call. Next, DAP 17 performs an address translation,block 82. Lastly, block 84 assembles the message including the addressof the dispatch call, the available resources, the port identity andtype. The message is then sent back to the target network 20 or 30-60 byblock 86. Block 86 then transfers control back to block 70 to wait forthe next message.

[0022] If the message type as determined by block 72 is a setup inprogress, block 72 transfers control to block 96. Block 96 determineswhether resources have already been assigned (as defined in the initialmessage). If the resources have been assigned, block 96 transferscontrol to block 104 via the yes path. If the resources have not alreadybeen assigned, block 96 transfers control to block 98 via the no path.Also, for an initial request message type, block 78 has transferredcontrol to block 98 via the yes path.

[0023] Block 98 determines what resources are required. Block 98 thentransfers control to block 100. Block 100 determines whether therequired resources are available. If not, block 100 transfers controlvia the no path to block 90 and the dispatch call is ended. If theresources are available, block 100 transfers control to block 102 viathe yes path.

[0024] Block 102 reserves the required resources and transfers controlto block 104. Earlier if the resources have already been assigned, block96 also transfers control to block 104 via the yes path. Block 104determines whether a response to the target of the dispatch call isrequired. If not, block 104 transfers control to block 108 via the nopath. If a response is required, block 104 transfers control to block106 via the yes path. Block 106 assembles a response message and sendsthe message to the target unit 31-62.

[0025] Block 106 then transfers control to block 108. If a response isrequired to the originator or source of the dispatch call, block 108transfers control to block 110. If no response to the originator isrequired, block 108 transfers control to block 70 which waits for thenext message. Block 110 assembles the response message. Block 112 thensends the response message to the source or originator and transferscontrol to block 70 to wait for the next message.

[0026] If block 72 determined that the message type was an incallmodification (such as add party, release, or bearer/voice packets),block 72 transfers control to block 88. Block 88 determines whether thereceived message is valid. If the received message is invalid, block 88transfers control to block 90 via the no path. Block 90 ends thedispatch call. If the received in-call message is valid, block 88transfers control to block 92 via the yes path. Block 92 translates themessageLastly, block 94 sends the appropriately converted message to theother party. Block 94 then transfers to block 70 to wait for the nextmessage.

[0027] Without transcoding, a voice message is converted between iRTP byiDEN RTP 16 and RTP by standard RTP 15. With transcoding vocoders usedby the end devices on 3 G and 2 G interfaces are different and the VSGWtranscodes the voice appropriately and converts the voice packetsbetween iRTP and RTP.

[0028] As can now be appreciated, a voice signaling gateway (VSGW) 10 isshown which supports interworking between iDEN and non-iDEN networks.This gateway provides the signaling and bearer path conversion oftraffic between the TDMA and non-TDMA networks. Further, this gatewayinterfaces iDEN network to various networks such as CDMA, GSM, 802.11 ortypical internet protocol networks. This invention does not require thatiDEN subscribers be aware that they are communicating with a non-iDENnetwork. Further, the invention does not require iDEN network elementsto be modified or changed.

[0029] Although the preferred embodiment of the invention has beenillustrated, and that form described in detail, it will be readilyapparent to those skilled in the art that various modifications may bemade therein without departing from the spirit of the present inventionor from the scope of the appended claims.

1. An arrangement for interworking a iDEN network with a plurality ofnon-iDEN networks, the arrangement comprising: voice signaling gateway(VSGW) means coupled to the plurality of non-iDEN networks and to theiDEN network; the coupling of the VSGW means to the iDEN networkincluding a plurality of connections for signaling and for bearertraffic; and the coupling of the VSGW means to tile plurality ofnon-iDEN network including signaling and bearer traffic connectionsbetween each of the plurality of non-iDEN networks and the VSGW means.2. The arrangement for interworking as claimed in claim 1, wherein thevoice signaling gateway (VSGW) means includes: a VSGW signalingcontroller for generating signaling information for the iDEN network andthe plurality of non-iDEN networks; and a VSGW bearer traffic controllerfor converting bearer traffic between the iDEN network and the pluralityof non-iDEN networks.
 3. The arrangement for interworking as claimed inclaim 2, wherein the VSGW signaling controller is coupled to the VSGWbearer traffic controller via a bearer control connection whereby theVSGW signaling controller controls bearer traffic interworking via theVSGW bearer traffic controller among the iDEN network and the pluralityof non-iDEN networks.
 4. The arrangement for interworking as claimed inclaim 2, wherein there is further included: a real time protocolconnection between the VSGW bearer traffic controller and each of theplurality of non-iDEN networks; and a iDEN real time protocol connectionbetween the VSGW bearer traffic controller and a dispatch audiocontroller of the iDEN network.
 5. The arrangement for interworking asclaimed in claim 2, wherein there is further included a signalingconnection between the VSGW signaling controller and each of theplurality of non-iDEN networks, the VSGW signaling controller providingon the signaling connection a specific protocol for interfacing witheach of the plurality of non-iDEN networks.
 6. The arrangement forinterworking as claimed in claim 2, wherein there is further included amobile application part signaling connection between the VSGW signalingcontroller and home location register means, the mobile application partsignaling connection providing location information.
 7. The arrangementfor interworking as claimed in claim 2, wherein there is furtherincluded a dispatch application. processor signaling connection betweenthe VSGW signaling controller and a dispatch application processor, thedispatch application processor signaling connection providing controlinformation for handling dispatch calls to and from the iDEN network. 8.The arrangement for interworking as claimed in claim 1, wherein theplurality of non-iDEN networks includes at least one of: code divisionmultiple access (CDMA) network; global system mobile (GSM) network;internet protocol (IP) network; and 802.11 type network.
 9. A method fornetwork interworking by a voice signaling gateway (VSGW) between a iDENnetwork and a plurality of non-iDEN networks, the method comprising thesteps of: determining that a request from the iDEN network or theplurality of non-iDEN networks is an initial request; determining adestination for the initial request; determining whether appropriateresources may be assigned to the initial request; and if the appropriateresources can be assigned, generating a list of the appropriateresources to meet the initial request.
 10. The method as claimed inclaim 9, wherein the step of determining the destination includes thesteps of: determining whether the destination is already known; and ifthe destination is not already known, determining the destination from adatabase.
 11. The method as claimed in claim 9, wherein there is furtherincluded a step of translating an address for response.
 12. The methodas claimed in claim 9, wherein the step of generating a list includesthe step of assembling a message including an address, the appropriateresources, a port, and a type.
 13. The method as claimed in claim 12,wherein there is further included a step of sending the assembledmessage to a designated target.
 14. The method as claimed in claim 13,wherein there is further included a step of waiting for a message.
 15. Amethod for network interworking by a voice signaling gateway (VSGW)between a iDEN network and a plurality of non-iDEN networks, the methodcomprising the steps of: determining whether a request from a source ora target is a setup request; determining whether resources have beenassigned to the setup request; if the resources have not been assigned,determining whether the resources are available; and sending a responsemessage to the source or the target of the request.
 16. The method asclaimed in claim 15, wherein if resources have not been assigned, thereis further included a step of determining required resources.
 17. Themethod as claimed in claim 16, wherein if the required resources areavailable there is further included a step of reserving the requiredresources by the VSGW.
 18. The method as claimed in claim 16, wherein ifthe required resources are unavailable there is further included a stepof ending a dispatch call.
 19. The method as claimed in claim 16,wherein the step of sending includes a step of determining whether aresponse to a target of a dispatch call is required.
 20. The method asclaimed in claim 19, wherein if the response to the target is required,there is further included the steps of: assembling the required resourceinto a message; and sending the message to the target of the dispatchcall.
 21. The method as claimed in claim 19, wherein if the response isnot to a target, there is further included a step of determining whetherthe response is to an originator of the dispatch call.
 22. The method asclaimed in claim 21, wherein if the response is to an originator of thedispatch call there is further included the steps of: assembling amessage including the required resources, address, port and type; andsending the message to the originator of the dispatch call.
 23. Themethod as claimed in claim 22, wherein there is further included a stepof waiting for a message by the VSGW.
 24. The method as claimed in claim22, wherein if the response is not to an originator of the dispatchcall, there is further included a step of waiting for a message.
 25. Amethod for network interworking by a voice signaling gateway (VSGW)between a iDEN network and a plurality of non-iDEN networks, the methodcomprising the steps of: determining that a received message is for amodification to an existing dispatch call; determining that the receivedmessage is valid; if the received message is valid, translating themessage using an appropriate protocol; and sending the translatedmessage to another party of the existing dispatch call.
 26. The methodas claimed in claim 25, wherein if the received message is invalid,there is further included a step of ending the existing dispatch call.